Selfmate paradox

The usual self-mating rules apply, with a restriction: Black may not make a move, which gives white the opportunity to a one-step mate. This black-out condition must be taken into account even by Schwarz, even if the white mat which is to be prevented is out of balance. Otherwise black can move as desired.
Black, of course, must first of all pay attention to the prohibition of self-check and to parry opposing checks; this is not a fairy format. If he has several possibilities to parry a check, he has to choose, if possible, between those who do not allow white to have a single mat.
In the serial mover self-mate paradox, the white move series breaks off not only in the case of a check, but also in the event that White could mate with the next series move, but Black has an intermediate move to which there is no single mate by white ,
Unless otherwise specified, the Paradox requirement shall apply from the game array. This is why positions are also illegal, for which Black had to violate the paradox.
(Heinz Zander, Problemkiste (117) VI 1998, S.218 / 219